The present invention relates to an improved apparatus for stripping articles from press ram. Conventional apparatuses of this type, as disclosed in U.S. Pat. Nos. 3,353,394 and 3,390,565 include a plurality of strippers supported in a stripper supporting ring and mounted so that they are distributed over the circumference of the press ram and have the shape of segments, wherein thinner legs of each stripper face the press ram. Each stripper is pivotable in its plane to a limited extent in the direction toward and away from the press ram and is also displaceable in the direction of the axis of the press ram to a limited degree. All strippers are under the effect of two elastic rings, one of which rings elastically bears on all strippers during stripping in the direction of the press ram axis with respect to the stripper supporting ring, and the other of these rings, which encompasses all of the strippers, urges the strippers to pivot inwardly in the radial direction. One disadvantage of this prior arrangement is the very limited elastic movability of the individual strippers in the direction of the press ram axis. Further, this conventional apparatus has the disadvantage that the elastic forces acting on the individual strippers in the direction of the press ram axis and radially inwardly cannot be adapted to the respective ambient operating conditions without an exchange of the elastic rings. Consequently, the intended adaptation of the position of the individual strippers to the shape of the stripping edge, which stripping edge is differently shaped from one hollow article to the next, is attained during stripping only if the resistance offered against the stripping action by the hollow article lies within a range corresponding to the elasticity of the ring. If the resistance is too low or too high, the conventional apparatus becomes inoperable, because there is either no compression at all or there is a complete compression up to the rearward end position of the ring. Corresponding remarks apply with respect to the pivoting action of the strippers and the force with which the strippers contact the hollow article during passage of the press ram with this hollow article, with consequent danger of damage to the surface of the article. This last-mentioned disadvantage is of special importance insofar as there are no means provided in the conventional device to remove the strippers during the operating cycle of the press ram in the radial direction outwardly so that they are sufficiently remote from the press ram to permit passage of the ram with the hollow article without any contact with the strippers.
Similar disadvantages are likewise present in another known apparatus disclosed in German Pat. No. 593,849.
It is contemplated by the present invention to arrange the position and bearing of the strippers so that the elastic forces with which the strippers come in contact with the stripping edge of the hollow article during the stripping step can be simply adapted to the respective resistance offered against the stripping action by the hollow article. The present invention also contemplates simultaneously providing a displaceability of the individual strippers in the direction of the press ram axis to a relatively large extent. With the arrangement of the present invention, it is provided that the strippers contact the irregularly shaped stripping edge of the hollow article under all conditions which may occur and also effect the stripping step without causing an appreciable deformation or canting of the hollow article. The invention is furthermore intended for eliminating also the danger of damage to the surface of the hollow article while the same is passing through the stripper supporting ring during the operating cycle of the press ram. This last-mentioned result is obtained by the provision of a rhythmic removal of the strippers from the space where the press ram passes through.
The present invention is particularly concerned with an apparatus for stripping drawn or extruded hollow articles from a press ram which includes a stripper supporting ring having several strippers distributed over the circumference of the press ram, which strippers are pivotally and elastically mounted with each stripper having the configuration of a double angle in its radial plane containing the axis of the press ram and the stripping surface of the stripper being provided on the leg of the double angle which faces the press ram.
According to the invention, with appropriately selected length of the stripping piston portions and the operating piston portions of the strippers, and with a sufficient movability thereof in the axial direction of the press ram, the end faces of the stripping piston portions can extend to such a degree and in such a different way beyond the end face of the forward ring portion that an adaptation is made possible to strongly irregularly formed stripping edges of the hollow articles. On the other hand, by a rhythmic actuation of the drive rotating the ring segments with respect to one another, the stripping piston portions are pivoted out of the passage space of the press ram during each operating cycle of the ram. In this process, each stripper pivots about the axis of its operating piston portion.
According to preferred embodiments of the present invention, the drive for the ring segments or portions needs to rotate the rings with respect to each other merely by an angle of a few degrees in one or the other direction. Consequently, the drive for rotating the rings can be constructed in a particularly simple manner as a cylinder-piston unit which is articulated on the one hand to the forward ring portion and, on the other hand, to the rearward ring portion.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.